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United States Patent | 5,254,992 |
Keen ,   et al. | October 19, 1993 |
A microprocessor (8) controlled power-saving electronic measuring system is disclosed. A load cell (1) generates an output signal indicative of the magnitude of the load applied to the cell (1). A DC power supply (2) is switched to supply the load cell (1) with power pulses (10) at varying frequencies and duty cycles determinable by the microprocessor (8) to optimize battery life. The microprocessor (8) determines the optimal duty cycle and frequency for the power pulses responsive to desired parameters. The circuitry of the present invention is located in close proximity to a temperature sensor (34) which accurately reads the temperatures of all of the components and compensates for all heat related inaccuracies simultaneously. The microprocessor (8) determines a temperature corrected value for the load cell (1) output via a previously programmed table containing the temperature response characteristics for the load cell (1) and the circuitry. In an over/under indicator mode, segments of the display (36) LED's are configured to graphically indicate whether the current weight on the scale is within a desired tolerance. A power saving sleep mode in described in which the system voltage level is reduced, and most of the circuitry is disabled.
Inventors: | Keen; Harry J. (St. Johnsbury, VT); Saucier; Leon E. (South Rygate, VT) |
Assignee: | Fairbanks Inc. (Kansas City, MO) |
Appl. No.: | 785539 |
Filed: | October 31, 1991 |
Current U.S. Class: | 341/119; 177/210R; 177/DIG.3; 307/152; 341/126 |
Intern'l Class: | H03M 001/06; G01G 003/14 |
Field of Search: | 341/119,110,126 177/DIG. 3,25.11,25.12,25.13,210 R,211 307/152 |
4238784 | Dec., 1980 | Keen et al. | 341/126. |